Antibodies are a type of tailor-made "poison" produced by white blood cells to kill foreign agents, notes Better Health Channel. For someone with Graves' disease, the antibodies uncontrollably stimulate the thyroid. Less than 1 percent of the population suffers from Graves' disease. Women have the disease at a rate of eight times more than men, and the disease is more common in middle age. The cause is unclear, but stress may contribute to Graves' disease and other autoimmune diseases because it affects immune-system responsivenesss.